1. Field of the Invention
The present invention relates to navigation systems and their intersection guidance methods, and specifically to a navigation system and its intersection guidance method allowing the driver to identify a traffic signal and arrow signal to be considered at a complex intersection.
2. Description of the Related Art
A navigation system searches for and displays a guidance route to a destination on a map. When the vehicle approaches an intersection on the guidance route, the navigation system shows an intersection view on the map or on one half of a split screen, indicates by an arrow the direction of travel at the intersection, and at the same time gives the direction of travel by a voice message. There have been proposed a variety of navigation systems with intersection guidance functions (for example, see Japanese Unexamined Patent Application Publication No. 2002-174527). In this known technique, a method of indicating the remaining distance is changed according to the distance to an intersection. When the vehicle is far from the intersection, the remaining distance is indicated by a bar graph. When the vehicle approaches the intersection, a vehicle position mark, which had been displayed in a fixed position, is moved along the guidance route according to the travel of the vehicle, while an arrow indicating the direction of travel is shortened to display the remaining distance.
At a complex intersection, such as a forked (four-way, five-way, or more) intersection, the driver may be confused about which one of a plurality of visible traffic signals to consider. It may also be possible that the driver is confused, at an intersection, as to which one of multiple indication arrows (arrow signals) for a traffic signal indicates the vehicle's direction of travel, because the arrow signals are oriented in various directions. Therefore, there is a possibility that the situations described above may cause traffic accidents and congestion at an intersection.
Although known navigation systems indicate, at a forked intersection, the direction of travel by an arrow and voice message, such known navigation systems do not clearly indicate which traffic signal and arrow signal the driver should refer to with respect to the direction of travel.